Azure DevOps Server Extended Client
Integrate with Azure DevOps Server, Microsoft Team Foundation Server and Azure DevOps Services from desktop-based Windows applications. Work with and manage version control, work items, and build, and other resources from your client application.

Microsoft Team Foundation Distributed Task Common Contracts
Integrate with Team Foundation Server 2017 and Azure DevOps Services from desktop-based, ASP.NET, and other Windows applications. Provides the models used to access the Distributed Task Service via public REST APIs.